An experimental investigation of the effects of thawed soil depth on rill flow velocity     

Xiaofeng Gao  Xiaonan Shi  Tingwu Lei  Huaqing Liu  Jiahui Yang 《水文研究》2021,35(2):e14043

Water flow velocity is an important hydraulic variable in hydrological and soil erosion models, and is greatly affected by freezing and thawing of the surface soil layer in cold high-altitude regions. The accurate measurement of rill flow velocity when impacted by the thawing process is critical to simulate runoff and sediment transport processes. In this study, an electrolyte tracer modelling method was used to measure rill flow velocity along a meadow soil slope at different thaw depths under simulated rainfall. Rill flow velocity was measured using four thawed soil depths (0, 1, 2 and 10 cm), four slope gradients (5°, 10°, 15° and 20°) and four rainfall intensities (30, 60, 90 and 120 mm·h⁻¹). The results showed that the increase in thawed soil depth caused a decrease in rill flow velocity, whereby the rate of this decrease was also diminishing. Whilst the rill flow velocity was positively correlated with slope gradient and rainfall intensity, the response of rill flow velocity to these influencing factors varied with thawed soil depth. The mechanism by which thawed soil depth influenced rill flow velocity was attributed to the consumption of runoff energy, slope surface roughness, and the headcut effect. Rill flow velocity was modelled by thawed soil depth, slope gradient and rainfall intensity using an empirical function. This function predicted values that were in good agreement with the measured data. These results provide the foundation for a better understanding of the effect of thawed soil depth on slope hydrology, erosion and the parameterization scheme for hydrological and soil erosion models.  相似文献   

Exploration prospects of oil and gas in the Northwestern part of the Offshore Indus Basin,Pakistan     

《China Geology》2020,3(4):633-642

Oil and gas resources are short in Pakistan and no commercially viable oil and gas sources have been yet discovered in its offshore areas up to now. In this study, the onshore-offshore stratigraphic correlation and seismic data interpretation were conducted to determine the oil and gas resource potential in the Offshore Indus Basin, Pakistan. Based on the comprehensive analysis of the results and previous data, it is considered that the Cretaceous may widely exist and three sets of source rocks may be developed in the Offshore Indus Basin. The presence of Miocene mudstones has been proven by drilling to be high-quality source rocks, while the Cretaceous and Paleocene–Eocene mudstones are potential source rocks. Tectonic-lithologic traps are developed in the northwestern part of the basin affected by the strike-slip faults along Murray Ridge. Furthermore, the Cretaceous and Paleocene–Eocene source rocks are thick and are slightly affected by volcanic activities. Therefore, it can be inferred that the northwestern part of Offshore Indus Basin enjoys good prospects of oil and gas resources.  相似文献   

Effect of Caliche Nodules on Soil Water Storage in the Northern Loess Plateau of China     

Tiexiong Gong  Yuanjun Zhu  Yunqiang Wang  Wei Hu  Ming'an Shao 《洁净——土壤、空气、水》2019,47(7)

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Evaluation of the temporal variations of groundwater storage and its interactions with climatic variables using GRACE data and hydrological models: A study from Turkey     

Behnam Khorrami  Orhan Gunduz 《水文研究》2021,35(3):e14076

Monitoring of the fluctuations of groundwater storage is particularly important in arid and semi-arid regions where water scarcity brings about various challenges. Remote sensing data and techniques play a preponderant role in developing solutions to environmental problems. The launch of Gravity Recovery and Climate Experiment (GRACE) satellites has eased the remote monitoring and evaluation of groundwater resources with an unprecedented precision over large scales. Within the scope of the current study, the latest release (RL06) of GRACE mass concentrations (Mascons) from Jet Propulsion Laboratory (JPL) dataset as well as Global Land Data Assimilation System (GLDAS) models of Noah and Catchment Land Surface Model (CLSM) were used to provide Groundwater Storage Anomalies (GWSA) over Turkey. The temporal interactions of the estimated GWSA with the climatic variables of precipitation and temperature (derived from the reanalysis datasets of CHELSA [Climatologies at High resolution for the Earth's Land Surface Areas] and FLDAS [the Famine Early Warning Systems Network Land Data Assimilation System], respectively) were investigated statistically. The results suggest that there is a descending trend (from 2003 to 2016) for Terrestrial Water Storage Anomalies (TWSA) and GWSA over Turkey with a total loss of 11 and 6 cm of water, respectively. The statistical analysis results also indicate that the monthly variations of GWSA over Turkey are highly correlated with precipitation and temperature at 2-month lag. The analysis of the climatology (long-term) values of monthly GWSA, precipitation and temperature also revealed high agreement between the variables.  相似文献   

Consistency of precipitation products over the Arabian Peninsula and interactions with soil moisture and water storage     

Youssef Wehbe  Marouane Temimi  Dawit T. Ghebreyesus  Adam Milewski  Hamid Norouzi  Elsy Ibrahim 《水文科学杂志》2018,63(3):408-425

The regional-scale consistency between four precipitation products from the GPCC, TRMM, WM, and CMORPH datasets over the Arabian Peninsula was assessed. Their macroscale relationships were inter-compared with soil moisture and total water storage (TWS) estimates from AMSR-E and GRACE. The consistency analysis was studied with multivariate statistical hypothesis testing and Pearson correlation metrics for the period from January 2000 to December 2010. The products and GRACE estimates were assessed over a representative sub-domain (United Arab Emirates) with available in situ well observations. Next, geographically temporally weighted regression (GTWR) was employed to examine the interdependencies among the peninsula’s hydrological components. The results showed GPCC-TRMM recording the highest correlation (0.85) with insignificant mean differences over more than 90% of the peninsula. The highest GTWR predictive performance of TWS (R² = 0.84) was achieved with TRMM forcing, which indicates its potential to monitor changes in TWS over the arid peninsular region.  相似文献   

生物土壤结皮铁代谢微生物组成及其功能基因对演替的响应     

王岩松  刘玉冰  王增如  赵丽娜  漆婧华  张雯莉 《中国沙漠》2020,40(3):193-200

采用微生物宏基因组学微阵列GeoChip 5.0技术，选择腾格里沙漠东南缘沙坡头地区不同年代人工固沙植被区的生物土壤结皮（BSC）为对象，分析BSC演替过程中参与铁代谢的功能微生物组成及其功能基因变化特征，研究微生物铁代谢对BSC演替的响应及调控。结果表明：真菌参与铁吸收和转运过程，古菌参与铁转运和贮存过程，细菌则在铁代谢吸收、转运和贮存过程中均起主要调控作用。门水平上，BSC铁代谢功能微生物组成变化对演替的响应不敏感，BSC铁代谢微生物主要为变形菌门（Proteobacteria）。BSC铁代谢功能基因多样性的显著提高和三类铁代谢过程基因信号强度达到最高水平需要经过61 a的演替。调控BSC铁吸收过程的主要功能基因为亚铁氧化酶编码基因iro；调控原核生物铁转运过程的主要功能基因，为羟基苯甲酰丝氨酸铁外膜转运体编码基因cirA和Fe（Ⅱ）转运蛋白编码基因feoB，真菌铁转运过程主要依靠含铁细胞转运体和铁氧化酶高亲和力的作用；调控铁贮存过程的主要功能基因为固定相类核蛋白编码基因dps。在BSC演替阶段末期，上述铁代谢功能基因强度的显著增加促进了微生物的铁代谢潜能。干旱、半干旱荒漠生态系统植被恢复过程中微生物铁代谢潜能的恢复需要较长时间。  相似文献   

Stochastic and analytical approaches for sediment accumulation in river reservoirs     

Tanju Akar 《水文科学杂志》2020,65(6):984-994

ABSTRACT

Sediment accumulation in a river reservoir is studied by stochastic time series models and analytical approach. The first-order moving average process is found the best for the suspended sediment discharge time series of the Juniata River at Newport, Pennsylvania, USA. Synthetic suspended sediment discharges are first generated with the chosen model after which analytical expressions are derived for the expected value and variance of sediment accumulation in the reservoir. The expected value and variance of the volume of sediment accumulation in the reservoir are calculated from a thousand synthetic time series each 38 years long and compared to the analytical approach. Stochastic and analytical approaches perfectly trace the observation in terms of the expected value and variability. Therefore, it is concluded that the expected value and variance of sediment accumulation in a reservoir could be estimated by analytical expressions without the cost of synthetic data generation mechanisms.  相似文献   

分布式数据库Greenplum在地震前兆数据存储中的应用     

陈晓琳  李盛乐  刘坚  刘珠妹 《地震研究》2020,(2):412-416,418

随着地震前兆观测台网的加密、采样率的提高,地震前兆观测数据量也在快速增加。在进行地震数据共享服务时,需要快速获得大量数据集,无疑对前兆共享数据库的数据处理能力提出了更高的要求。针对这一问题,提出基于Greenplum数据库的地震前兆数据存储设计方案。通过搭建Greenplum分布式数据库环境,实现了海量前兆数据的快速处理,并与传统Oracle数据库进行对比,结果表明:Greenplum数据库读取前兆数据耗时更低,对于大批量数据的读取操作,Greenplum数据库的优势更加明显;Greenplum数据库良好的可扩展性和对应用编程接口(JDBC、ODBC)的支持,使得其在前兆数据分析处理中的应用前景广阔。  相似文献   

Sediment and nutrient storage in a beaver engineered wetland          下载免费PDF全文

Alan Puttock  Hugh A. Graham  Donna Carless  Richard E. Brazier 《地球表面变化过程与地形》2018,43(11):2358-2370

Beavers, primarily through the building of dams, can deliver significant geomorphic modifications and result in changes to nutrient and sediment fluxes. Research is required to understand the implications and possible benefits of widespread beaver reintroduction across Europe. This study surveyed sediment depth, extent and carbon/nitrogen content in a sequence of beaver pond and dam structures in South West England, where a pair of Eurasian beavers (Castor fiber) were introduced to a controlled 1.8 ha site in 2011. Results showed that the 13 beaver ponds subsequently created hold a total of 101.53 ± 16.24 t of sediment, equating to a normalised average of 71.40 ± 39.65 kg m². The ponds also hold 15.90 ± 2.50 t of carbon and 0.91 ± 0.15 t of nitrogen within the accumulated pond sediment. The size of beaver pond appeared to be the main control over sediment storage, with larger ponds holding a greater mass of sediment per unit area. Furthermore, position within the site appeared to play a role with the upper‐middle ponds, nearest to the intensively‐farmed headwaters of the catchment, holding a greater amount of sediment. Carbon and nitrogen concentrations in ponds showed no clear trends, but were significantly higher than in stream bed sediment upstream of the site. We estimate that >70% of sediment in the ponds is sourced from the intensively managed grassland catchment upstream, with the remainder from in situ redistribution by beaver activity. While further research is required into the long‐term storage and nutrient cycling within beaver ponds, results indicate that beaver ponds may help to mitigate the negative off‐site impacts of accelerated soil erosion and diffuse pollution from agriculturally dominated landscapes such as the intensively managed grassland in this study. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

An Investigation of the Factors Affecting Saline Ice Melting Processes and Desalination          下载免费PDF全文

Yue Zhang  Jingsong Yang  Rongjiang Yao 《洁净——土壤、空气、水》2018,46(8)

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